is versatile, compact and easy to use. Micropower opera-
tion benefits portable and battery-powered equipment. At
100kHz, the LTC6906 consumes 12μA on a 3.3V supply.
A single resistor programs the oscillator frequency over
a 10:1 range with better than 0.5% initial accuracy. The
output frequency can be divided by 1, 3 or 10 to span a
100:1 total frequency range, 10kHz to 1MHz.
The LTC6906 is easily programmed according to this
simple formula:
⎧
10,
⎪
1MHz
⎛
100k
⎞
=
•⎜
, N
= ⎨
3,
⎟
N
⎝
R
SET
⎠
⎪
⎩
1,
DIV Pin
=
V
+
DIV Pin
=
Open
DIV Pin
=
GND
Supply Current: 12μA at 100kHz
<0.65% Frequency Accuracy (from 0°C to 70°C)
Frequency Range: 10kHz to 1MHz
One Resistor Sets the Oscillator Frequency
Single Supply: 2.25V to 5.5V
–40°C to 125°C Operating Temperature Range
No Decoupling Capacitor Needed
Start-Up Time Under 200μs at 1MHz
First Cycle After Power-Up is Accurate
150Ω CMOS Output Driver
Low Profile (1mm) SOT-23 (ThinSOT™) Package
APPLICATIONS
n
n
n
n
n
ƒ
OUT
Low Cost Precision Programmable Oscillator
Rugged, Compact Micropower Replacement for
Crystal and Ceramic Oscillators
High Shock and Vibration Environments
Portable and Battery-Powered Equipment
PDAs and Cellular Phones
No decoupling capacitor is needed in most cases, yield-
ing an extremely compact solution occupying less than
20mm2. Contact LTC Marketing for a version of the part
with a shutdown feature or lower frequency operation.
The LTC6906 is available in the 6-lead SOT-23 (ThinSOT)
package.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners.
TYPICAL APPLICATION
Micropower Clock Generator
90
NO DECOUPLING
CAPACITOR
NEEDED
LTC6906
2.25V TO 3.6V
10
3
1
V
+
GND
DIV
OUT
GRD
SET
R
SET
100k TO 1M
6906 TA01
Typical Supply Current vs Frequency
80
POWER SUPPLY CURRENT (A)
C
L
= 5pF
T
A
= 25°C
V
+
= 3.6V
10kHz TO 1MHz
70
60
50
40
30
20
10
0
0
200
V
+
= 2.25V
400
600
800
FREQUENCY (kHz)
1000
1200
6906 TA01b
6906fc
1
LTC6906
ABSOLUTE MAXIMUM RATINGS
(Note 1)
V
+
................................................................ –0.3V to 6V
DIV to GND .....................................–0.3V to (V
+
+ 0.3V)
SET to GND .....................................–0.3V to (V
+
+ 0.3V)
GRD to GND ....................................–0.3V to (V
+
+ 0.3V)
PIN CONFIGURATION
TOP VIEW
OUT 1
GND 2
DIV 3
6 V
+
5 GRD
4 SET
Operating Temperature Range (Note 7)
LTC6906C ............................................–40°C to 85°C
LTC6906I .............................................–40°C to 85°C
LTC6906H .......................................... –40°C to 125°C
Specified Temperature Range (Note 7)
LTC6906C ................................................ 0°C to 70°C
LTC6906I .............................................–40°C to 85°C
LTC6906H .......................................... –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
JMAX
= 150°C,
θ
JA
= 230°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC6906CS6#PBF
LTC6906IS6#PBF
LTC6906HS6#PBF
LEAD BASED FINISH
LTC6906CS6
LTC6906IS6
LTC6906HS6
TAPE AND REEL
LTC6906CS6#TRPBF
LTC6906IS6#TRPBF
LTC6906HS6#TRPBF
TAPE AND REEL
LTC6906CS6#TR
LTC6906IS6#TR
LTC6906HS6#TR
PART MARKING*
LTBJN
LTBJN
LTBJN
PART MARKING*
LTBJN
LTBJN
LTBJN
PACKAGE DESCRIPTION
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
PACKAGE DESCRIPTION
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
SYMBOL
Δf
PARAMETER
Frequency Accuracy (Notes 2, 3, 9)
CONDITIONS
V
+
= 2.7V to 3.6V
100kHz ≤ f ≤ 1MHz
100kHz ≤ f ≤ 1MHz, LTC6906C
100kHz ≤ f ≤ 1MHz, LTC6906I
f = 1MHz, LTC6906H
f = 100kHz, LTC6906H
100kHz ≤ f ≤ 1MHz
100kHz ≤ f ≤ 1MHz, LTC6906C
100kHz ≤ f ≤ 1MHz, LTC6906I
f = 1MHz, LTC6906H
f = 100kHz, LTC6906H
l
l
l
l
l
l
l
l
ELECTRICAL CHARACTERISTICS
MIN
TYP
±0.25
MAX
±0.5
±0.65
±1.3
±1.3
±2.2
±0.7
±0.85
±1.3
±1.3
±2.2
UNITS
%
%
%
%
%
%
%
%
%
%
6906fc
V
+
= 2.25V
±0.25
2
LTC6906
ELECTRICAL CHARACTERISTICS
SYMBOL
R
SET
Δf/ΔT
Δf/ΔV
PARAMETER
Frequency-Setting Resistor Range
Frequency Drift Over Temp (Note 3)
Frequency Drift Over Supply (Note 3)
Timing Jitter (Note 4)
R
SET
= 316k
V
+
= 2.25V to 3.6V, 100k ≤ R
SET
≤ 1000k
Pin 3 = V
+
, 100k ≤ R
SET
≤ 1000k
Pin 3 = Open, 100k ≤ R
SET
≤ 1000k
Pin 3 = 0V, 100k ≤ R
SET
≤ 1000k
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
CONDITIONS
l
l
MIN
100
TYP
±0.005
0.06
0.03
0.07
0.15
300
MAX
1000
UNITS
kΩ
%/°C
%/V
%
%
%
ppm/√kHr
S
f
DC
V
+
I
S
Long-Term Stability of Output Frequency Pin 3 = V
+
Duty Cycle
Operating Supply Range (Note 8)
Power Supply Current
R
SET
= 1000k, Pin 3 = 0V, R
L
= 10M
(DIV = 1, f
OUT
= 100kHz)
R
SET
= 100k, Pin 3 = 0V, R
L
= 10M
(DIV = 1, f
OUT
= 1MHz)
V
+
= 3.6V
V
+
= 2.25V
V
+
= 3.6V
V
+
= 2.25V
V
+
= 3.6V
V
+
= 2.25V
V
+
= 3.6V
V
+
= 2.25V
Pin 3 = V
+
Pin 3 = 0V
V
+
= 3.6V
V
+
= 2.25V
I
OH
= –100μA
I
OH
= –1mA
I
OH
= –100μA
I
OH
= –1mA
I
OL
= 100μA
I
OL
= 1mA
I
OL
= 100μA
I
OL
= 1mA
45
2.25
50
12.5
10.0
78
60
55
3.6
18
15
100
80
%
V
μA
μA
μA
μA
V
V
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
V
IH
V
IL
I
DIV
V
OH
High Level DIV Input Voltage
Low Level DIV Input Voltage
DIV Input Current (Note 5)
High Level Output Voltage (Note 5)
3.1
2.05
0.5
0.2
–2
3.40
2.80
2.15
1.75
1
–1
3.59
3.30
2.2
2.0
0.02
0.15
0.03
0.30
10
25
10
25
0.2
0.8
0.1
0.5
2
V
V
μA
μA
V
V
V
V
V
V
V
V
ns
ns
ns
ns
V
OL
Low Level Output Voltage (Note 5)
V
+
= 3.6V
V
+
= 2.25V
t
r
t
f
VGS
OUT Rise Time (Note 6)
OUT Fall Time (Note 6)
GRD Pin Voltage Relative to SET Pin
Voltage
V
+
= 3.6V
V
+
= 2.25V
V
+
= 3.6V
V
+
= 2.25V
–10μA ≤ I
GRD
≤ 0.3μA
l
–10
10
mV
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
Some frequencies may be generated using two different values of
R
SET
. For these frequencies, the error is specified assuming that the larger
value of R
SET
is used.
Note 3:
Frequency accuracy is defined as the deviation from the f
OUT
equation.
Note 4:
Jitter is the ratio of the peak-to-peak deviation of the period to the
mean of the period. This specification is based on characterization and is
not 100% tested.
Note 5:
Current into a pin is given as a positive value. Current out of a pin
is given as a negative value.
Note 6:
Output rise and fall times are measured between the 10% and
90% power supply levels.
Note 7:
The LTC6906C is guaranteed to meet specified performance from
0°C to 70°C. The LTC6906C is designed, characterized and expected to
meet specified performance from –40°C to 85°C but is not tested or QA
sampled at these temperatures. The LTC6906I is guaranteed to meet
specified performance from –40°C to 85°C.
Note 8:
Consult the Applications Information section for operation with
supplies higher than 3.6V.
Note 9:
Test conditions reflect the master oscillator frequency. The output
divider is functionally tested and divided frequency accuracy is guaranteed
by design.
6906fc
3
LTC6906
TYPICAL PERFORMANCE CHARACTERISTICS
Typical Frequency Error
vs Power Supply
0.50
0.40
0.30
FREQUENCY ERROR (%)
FREQUENCY ERROR (%)
0.20
0.10
0
R
SET
= 1M
R
SET
= 100k
0
3.6V
–1
3.6V
–2
–3
–4
–5
–50 –30 –10 10 30 50 70 90 110 130 150
TEMPERATURE (°C)
6906 G01
6906 G02
Typical Frequency Error
vs Temperature
2
1
R
SET
= 100k
2.25V
ERROR (%)
0.50
0.40
0.30
0.20
2.25V
0.10
0
Typical Frequency Error vs R
SET
V
+
= 2.25V
V
+
= 5V
–0.10
–0.20
–0.30
–0.40
–0.10
–0.20
–0.30
–0.40
–0.50
0
200
400
R
SET
= 1M
–0.50
2.25
3
4
SUPPLY VOLTAGE (V)
5
600
800
R
SET
(kΩ)
1000
1200
6906 G03
Typical Supply Current
vs Frequency
90
80
POWER SUPPLY CURRENT (A)
70
60
50
40
30
20
10
0
0
200
400
600
800
FREQUENCY (kHz)
1000
1200
V
+
= 2.25V
C
L
= 5pF
T
A
= 25°C
POWER SUPPLY CURRENT (A)
V
+
= 3.6V
200
180
160
140
120
100
80
60
40
20
0
Typical Supply Current
vs Load Capacitance
T
A
= 25C
1MHz, 3.6V
SET PIN VOLTAGE (V)
0.80
0.75
0.70
0.65
0.60
0.55
0.50
0.45
0.40
0.35
100kHz, 2.25V
0
20
10
30
LOAD CAPACITANCE (pF)
40
6906 G05
V
SET
vs Temperature (V
SET
is the
Voltage Measured at the R
SET
Pin)
R
SET
= 100k
1MHz, 2.25V
V
SET
AT
V
+
= 3.6V
V
SET
AT
V
+
= 2.25V
100kHz, 3.6V
0.30
–60 –40 –20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
6906 G06
6906 G04
Typical Supply Current
vs Temperature, 1MHz
90
85
SUPPLY CURRENT (A)
80
75
70
65
60
55
–60 –40 –20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
6906 G07
Typical Supply Current
vs Temperature, 100kHz
18
17
16
SUPPLY CURRENT (A)
15
14
13
12
11
10
9
8
–50 –30 –10 10 30 50 70 90 110 130 150
TEMPERATURE (°C)
6906 G08
C
L
= 5pF
I
SUPPLY
C
L
= 5pF
AT V
+
= 3.6V
I
SUPPLY
AT V
+
= 3.6V
I
SUPPLY
AT V
+
= 2.25V
I
SUPPLY
AT V
+
= 2.25V
6906fc
4
LTC6906
PIN FUNCTIONS
OUT (Pin 1):
Oscillator Output. The OUT pin swings from
GND to V
+
with an output resistance of approximately
150Ω. For micropower operation, the load resistance must
be kept as high as possible and the load capacitance as
low as possible.
GND (Pin 2):
Ground.
DIV (Pin 3):
Divider Setting Input. This three-level input
selects one of three internal digital divider settings, de-
termining the value of N in the frequency equation. Tie to
GND for ÷1, leave floating for ÷3 and tie to V
+
for ÷10.
When left floating, the LTC6906 pulls Pin 3 to mid-supply
with a 2.5M resistor. When Pin 3 is floating, care should
be taken to reduce coupling from the OUT pin and its
trace to Pin 3. Coupling can be reduced by increasing the
physical space between traces or by shielding the DIV pin
with grounded metal.
SET (Pin 4):
Frequency Setting Resistor Input. Connect
a resistor, R
SET
, from this pin to GND to set the oscillator
frequency. For best performance use a precision metal- or
thin-film resistor of 0.5% or better tolerance and 50ppm/°C
or better temperature coefficient. For lower accuracy ap-
plications, an inexpensive 1% thick-film resistor may be
used. Limit the capacitance in parallel with R
SET
to less
than 10pF to reduce jitter and to ensure stability. Capaci-
tance greater than 10pF could cause the LTC6906 internal
feedback circuits to oscillate. The voltage on the SET pin
is approximately 650mV and decreases with temperature
by about –2.2mV/°C.
GRD (Pin 5):
Guard Signal. This pin can be used to reduce
PC board leakage across the frequency setting resistor,
R
SET
. The GRD pin is held within a few millivolts of the
SET pin and shunts leakage current away from the SET pin.
To control leakage, connect a bare copper trace (a trace
with no solder mask) to GRD and loop it around the SET
pin and all PC board metal connected to SET.
V
+
(Pin 6):
Voltage Supply (2.25V to 3.6V). This supply
is internally decoupled with a 20Ω resistor in series with
an 800pF capacitor. No external decoupling capacitor is
A flag to another clock domain
If the signal that needs to cross the clock domains is just a pulse (i.e. it lasts just one clock cycle), we call it a "flag". The previous design u ......
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